Radiographic evidence of posterior lumbar interbody fusion with an emphasis on computed tomographic scanning

The ideal result of a successful posterior lumbar interbody fusion is a bony arthrodesis across the disc space. Evidence for the presence of fusion has been trabeculation on plain roentgenograms, lack of motion on stress films, and osteosynthesis across the graft-host interface on tomography. However, none of the above is entirely conclusive. Computed tomographic scanning affords a better assessment of the stages of arthrodesis by examination of the remodeling processes. When a graft is totally remodeled and assumes the function of the host bone, the vertebral body in this case, then anatomic fusion or bony arthrodesis has been achieved. In autogeneic graft techniques, this occurs about nine to 12 months after surgery. Initially, there is formation of a peripheral cortical ring phenomenon and then a gradual remodeling of the centrum to cancellous bone and bone marrow.